Disk drives are widely used in computers and data processing systems for storing information in digital form. A typical disk drive includes an actuator motor, an E-block, one or more storage disks and one or more head suspension assemblies. The actuator motor moves the E-block relative to the storage disks. The E-block includes one or more actuator arms for positioning the one or more head suspension assemblies. Each head suspension assembly includes a slider and a read/write head.
Each storage disk typically includes a data storage surface on each side of the storage disk. The data storage surfaces are divided into a plurality of tracks. FIG. 1 is a cross-sectional view of an example of a portion of a prior art storage disk 18P. The storage disk 18P illustrated in FIG. 1 is formed beginning with a body region 58P made from an aluminum alloy. Layers of differing materials having varying thicknesses are symmetrically built up onto both sides of the body region 58P using plating or sputter depositing.
For example, moving outward from the body region 58P, the next layer can be a sublayer 70P made from a nickel alloy. The subsequent layer can be an underlayer 72P formed from a chromium alloy. Further, a magnetic layer 74P, an overcoat layer 76P and a lubricating layer 78P can be added to each side of the storage disk 18P. These layers usually vary in thickness from layer to layer. However, from one side of the storage disk 18P to the other, the thickness of each layer is substantially identical.
Recently, disk drives are being manufactured which utilize a single storage disk having only one data storage surface and one head suspension assembly (“one head disk drives”). These disk drives offer various advantages over disk drives having multiple storage surfaces, including a decreased complexity, i.e. requiring fewer mechanical and electrical components. For example, one head disk drives do not necessarily require the use of an E-block because only one actuator arm is needed to support the one head suspension assembly. As a consequence, the relative simplicity of one head disk drives can yield fewer reading and writing errors, resulting in increased accuracy and performance. Further, one head disk drives are typically more robust, easier to assemble, more physically compact and less costly to manufacture.
Moreover, the need to reduce data access times has led to increasing the rotational speed of the one or more storage disks. Because of the increased speed, the rotating storage disk(s) can generate significant air turbulence within the disk drive. Increased air turbulence can lead to unwanted vibration of the storage disk(s), and can effectively magnify any slight imbalance or other imperfections in the storage disk(s). For example, air turbulence can generate regions of low pressure near the storage disk(s), which are then filled by air rushing in because of the pressure differential. This repeated cycle causes chaotic and random flutter or wobble of the storage disk(s), making accurate track following more difficult.
Additionally, flutter or wobble of the storage disk can cause unwanted contact with the slider, resulting in damage to the head suspension assembly, damage to the storage disk and/or the loss of data. Moreover, vibration of the storage disk can result in acoustical problems, which in applications such as digital video cameras, for example, can lower the ultimate sound recording quality.
In addition, in order to increase storage capacity, storage disks are being manufactured with increased track density, i.e. more tracks per inch. In conventional disk drives, each slider rides on an air bearing generated by rotation of the storage disk. The separation between the slider and the disk surface during rotation of the storage disk is referred to as the flying height. As track density increases, the flying height must necessarily decrease in order to maintain accuracy of the disk drive. Currently, flying heights can be 20 nanometers or less. A drawback of such low flying heights is that even slight vibration or imbalance of the storage disk can cause the slider to crash into the storage disk.
In light of the above, the need exists to provide a reliable, simple, and efficient disk drive. Another need exists to provide a storage disk that inhibits track misregistration, inhibits vibration, and/or reduces the amount of fluid turbulence around the storage disk. Yet another need exists to provide a disk drive utilizing a single storage disk, which is relatively easy and cost effective to manufacture, assemble and use.